Editor's Note: CR4 would like to thank Dick Cawley for contributing this final installment in GEA Consulting's Refrigerant series. Click here for Part 5.

The HVAC&R industry - after spending considerable time and money converting to ozone friendly refrigerants - is now searching for alternatives with low global warming potential and short atmospheric life. Good choices are being formulated by chemical companies; and, as before, natural refrigerants are being considered.

The purpose for this note is to caution those exploring alternative refrigerants to not simply focus on system conditions that occur when equipment is being tested for rating purposes. Many products are required to perform as heat pumps, and they must necessarily encounter - and be required to operate under - extreme ambient conditions such as -20 F and 115 F. In these cases, relative efficiency is important, but also the equipment's life and reliability must not be jeopardized. While the extreme conditions occur during a relatively small percentage of equipment operation, they must nevertheless be taken into account.

Table1. is intended to show typical operating conditions for heat pumps when heating and cooling. Other products such as low temperature refrigeration units would also need to be studied through a full operating range.

The conditions marked in red are those tested for rating purposes. The others are just as important for reliability and efficiency. As you transition to new refrigerants make sure you have fully tested your products over the full range to assure customer satisfaction.

Further Reading in the Refrigerant Series:

Six Keys to a Successful Refrigerant Transition (Part 1)

Keys to a Successful Refrigerant Transition (Part 2)

There is No "Perfect Refrigerant"! (Part 3)

Beyond the Nine Dots of Refrigerant Environmental Properties (Part 4)

Refrigerant Transition - Follow the Leaders (Part 5)